Fluids viscosity determination by means of uncalibrated AFM cantilevers

1
Fluids viscosity determination by means of
uncalibrated AFM cantilevers
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
Massimiliano Papi Università Cattolica
SC-Istituto di Fisica
2
Atomic Force Microscopy
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
3
Why AFM?
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
The spontaneous beating of live myocyte cells can
be monitored directly by AFM. (from Domke et
al., 1999.)
4
AFM Application in Biology
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
5
Frequency Spectra
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
Simple harmonic oscillator
6
General Theory and Viscosity
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
Viscosity
Cantilever
(length, width, thickness, density, elasticity)
7
Calibration or Analogy
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
Time consuming Ropture risk
8
Approximation
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
9
Master Curve
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
b1
One-point calibration
10
Summary
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
-Explicit expression relating viscosity and
resonance frequency -Override the knowledge of
cantilever geometry
M. Papi, G. Arcovito, M. De Spirito, M. Vassalli,
B. Tiribilli. Applied Physics Letters, (2006) 88,
194102. Fluids viscosity determination by means
of uncalibrated AFM cantilevers.
11
Acknowledgements
Dott M. Vassalli Dott. B.Tiribilli
Istituto Sistemi Complessi, CNR, Firenze
12
Viscosity of Flexible Polymers
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006
For short DNA oligonucleotides which behave as
rigid rods in solution
For longer DNAs, which behave as flexible coils
13
Operation mode
S.I.B.P.A. Palermo, 17 - 21 Settembre 2006